The present invention relates to a master alloy for a sputtering target, which enables the deposition of a film with a uniform quality by achieving uniformity of the composition of the raw material powder and the internal texture through use of the master alloy; and a method of producing the sputtering target.
As a next-generation barrier metal, a combination of alloy elements comprising the characteristics as an alloy film considered to be a candidate of a barrier film to be used as a “pair” with a Cu seed layer, and a production method thereof are being desired.
For example, in cases that the foregoing alloy is an alloy containing X as the main component and further containing a Y component, it is normally used as an alloy (XY alloy) in which the Y component falls within a range of 0.1 to 40 at %. In the case of this kind of alloy, in a combination of X having a high melting point (for instance, Ta: melting point of 3017° C.) and Y having a low boiling point (for instance, Mn: boiling point of 2061° C.), Y will become volatilized under the conditions of melting X, and therefore it is impossible to control the composition with the melting method.
When reviewing publications, Patent Document 1 describes a sputtering target capable of depositing an antiferromagnetic reinforced film having high compositional uniformity, an antiferromagnetic film, a magnetoresistive sensor comprising said film, a magnetic head, and a magnetoresistive effect-type random access memory.
Specifically, Patent Document 1 describes a sputtering target composed of at least one type of element selected from nickel, palladium, platinum, cobalt, rhodium, iridium, vanadium, niobium, tantalum, copper, silver, gold, ruthenium, osmium, chromium, molybdenum, tungsten and rhenium, and manganese, wherein the number of defects per a sputtered surface of 1 cm2 is 10 defects or less.
Furthermore, Patent Document 1 describes an antiferromagnetic film which is deposited using the foregoing sputtering target, a magnetoresistive sensor comprising the foregoing antiferromagnetic film, a tunnel magnetoresistive sensor comprising the foregoing antiferromagnetic film, a magnetic head comprising the foregoing magnetoresistive sensor, and a magnetoresistive effect-type random access memory comprising the foregoing tunnel magnetoresistive sensor.
Furthermore, Patent Document 2 describes a sputtering target composed of at least one type of R element selected from Ni, Pd, Pt, Co, Rh, Ir, V, Nb, Ta, Cu, Ag, Au, Ru, Os, Cr, Mo, W and Re, and Mn, wherein the sputtering target comprises, as at least a part of the target texture, at least one type selected from an alloy phase and a compound phase of the R element and Mn; and further describes an antiferromagnetic film formed by using the foregoing sputtering target, and a magnetoresistive sensor.
Furthermore, Patent Document 3 describes a sputtering target composed of at least one type of R element selected from Ni, Pd, Pt, Co, Rh, Ir, V, Nb, Ta, Cu, Ag, Au, Ru, Os, Cr, Mo, W and Re, and Mn, wherein the oxygen content in the sputtering target is 1 wt % or less (including 0). The antiferromagnetic film 3 is obtained by subjecting this kind of sputtering target to sputter deposition. Patent Document 3 describes that the antiferromagnetic film 3 is used, for instance, as an exchange coupled film 2 by being laminated with a ferromagnetic film 4, and that this kind of exchange coupled film 2 is used in a magnetoresistive sensor or the like.
Nevertheless, all of these Patent Documents encounter the problem where, in cases where one of the alloy components has a high melting point and the other component has a low boiling point, one of the metal components become volatilized upon melting these components, and the intended alloy composition will undergo a change and become uncontrollable. But no solution for resolving the foregoing problem is disclosed.